In drywalling systems, particularly in commercial operations where metal studs are commonly used, an installation of a double sided wall proceeds by first positioning and fixing header and footer channels. A first stud on one lateral edge of the wall will normally be secured to the header and footer channels, and remaining studs are loosely positioned in the channels. A drywall panel, which may typically measure four feet wide by the height of the studs up to about twelve feet, is then screwed to the channels and the first stud by a first operator, working from the obverse side of the panel. A second operator, working from the reverse side, positions the remaining studs successively, while the first operator inserts screws through the panel and stud.
Generally speaking the operators will pre-mark the obverse face of the panel with pencil lines located at modular intervals, usually on sixteen or twenty-four inch centers. The second operator will normally use a scrap of lumber cut to the appropriate length to form a spacer. Disadvantages of this proceedure is that it is time consuming, and that errors in positioning any stud may be repeated in positioning successive studs. In the event that long panels are positioned horizontally on the studs, positioning errors can be appreciable. Specifications normally required that panel retaining screws be inserted into the studs at eight inch intervals along the periphery thereof, and at sixteen inch intervals in the field thereof. Generally the operators will gauge the distance between adjacent screws by eye, and it is often found that fewer screws than are specified are used.